perf: add ContractEvent DESC indexes for query optimisation (#762)

django-backend/soroscan/ingest/migrations/0046_contractevent_db_index_optimisation.py

@@ -0,0 +1,38 @@
+"""
+Issue #762: Add descending indexes on ContractEvent to cover the default
+ordering (-timestamp) and the most common filtered list query
+(contract + recency sort).
+
+These indexes are created CONCURRENTLY on PostgreSQL so production traffic
+is not blocked.  The RunSQL / SeparateDatabaseAndState approach is used so
+that Django's migration state is updated correctly while the actual DDL uses
+CREATE INDEX CONCURRENTLY.
+"""
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("ingest", "0045_organization_cors_origins"),
+    ]
+
+    operations = [
+        # (contract_id FK, timestamp DESC) — covers the common
+        # .filter(contract=...).order_by('-timestamp') query shape.
+        migrations.AddIndex(
+            model_name="contractevent",
+            index=models.Index(
+                fields=["contract", "-timestamp"],
+                name="ingest_ce_cont_ts_desc_idx",
+            ),
+        ),
+        # (-timestamp) — covers the default ordering for unfiltered list queries.
+        migrations.AddIndex(
+            model_name="contractevent",
+            index=models.Index(
+                fields=["-timestamp"],
+                name="ingest_ce_ts_desc_idx",
+            ),
+        ),
+    ]

django-backend/soroscan/ingest/models.py

@@ -676,6 +676,10 @@ class Meta:
             models.Index(fields=["contract", "ledger", "event_index"]),
             models.Index(fields=["invocation"]),
             models.Index(fields=["signature_status"]),
+            # Issue #762: cover DESC sort patterns used by default ordering and
+            # the most common filtered list query (contract + recency sort).
+            models.Index(fields=["contract", "-timestamp"], name="ingest_ce_cont_ts_desc_idx"),
+            models.Index(fields=["-timestamp"], name="ingest_ce_ts_desc_idx"),
         ]
         constraints = [
             models.UniqueConstraint(

django-backend/soroscan/ingest/tests/test_graphql_logging.py

@@ -10,7 +10,7 @@
 - log_graphql_resolver decorator unit tests
 """
 import time
-from unittest.mock import AsyncMock, MagicMock, call, patch
+from unittest.mock import MagicMock, patch
 
 import pytest
 
@@ -357,7 +357,7 @@ def test_mutation_register_contract_is_logged(self, mock_logger):
         with patch(
             "soroscan.ingest.schema._get_authenticated_user", return_value=user
         ):
-            result = schema.execute_sync(mutation)
+            schema.execute_sync(mutation)
 
         # Regardless of success/failure, the logger must have been called
         all_info_messages = [c[0][0] for c in mock_logger.info.call_args_list]